VITALITY OF SEEDS. 25 



hand. I am not aware that any thorough search 

 has ever been made for them. ' 



Let us now turn to the second part of our sub- 

 ject and re-examine some of the cases which have 

 been presented, and see to what extent they appear 

 well founded, and how far they are supported by 

 other and more direct evidence. Let us see what 

 has been done in the way of direct observation and 

 experiment to determine the limit of vitality in 

 seeds, and notice whether any explanations can be 

 afforded to account for what, if true, are certainly 

 remarkable instances of duration of life. For seeds 

 are living objects, and require, like all other living 

 things, a constant supply of food to support life; 

 and as they have no means of supplying this out- 

 side of themselves, we come, by this course of rea- 

 soning, to the idea that there must necessarily be 

 some limit to the duration of their vitality, however 

 abundant their supply of stored up food may be. 

 We know that under ordinary conditions seeds vary 

 in their limit of vitality; hence we may suppose 

 that under even the most favorable conditions they 

 will also vary. The seeds which in ordinary exper- 

 ience keep the longest are seldom those which are 

 of the largest size, hence we infer that amount of 

 available food is not the most important feature in 



* In a recent article published in the Forum, Prof. 

 Winchell shows that there is reason to doubt the belief 

 in a continuous continental glacier. 



